The Forerunners had an advanced grasp of slipspace bubbles and used variations of the timelock concept for a number of purposes. One of these was the slipspace field pod, a stasis pod capable of suspending its occupants in time.[5] Forerunner Durances were traditionally timelocked after the last impressions of a deceased Forerunner were enclosed within.[6] The Forerunners were also capable of creating reverse timelock fields, in which time passed at a vastly more rapid pace than within normal space. The IsoDidact used a prison cage containing a reverse timelock to execute the Primordial on Installation 07, forcing the being to disintegrate via the process of entropy through the artificially-induced passage of a billion years.[7]